WO2007071467A1 - Prismatic films for optical applications - Google Patents

Prismatic films for optical applications Download PDF

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Publication number
WO2007071467A1
WO2007071467A1 PCT/EP2006/066963 EP2006066963W WO2007071467A1 WO 2007071467 A1 WO2007071467 A1 WO 2007071467A1 EP 2006066963 W EP2006066963 W EP 2006066963W WO 2007071467 A1 WO2007071467 A1 WO 2007071467A1
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WO
WIPO (PCT)
Prior art keywords
coextruded
thickness
layer
film
base film
Prior art date
Application number
PCT/EP2006/066963
Other languages
German (de)
French (fr)
Inventor
Jann Schmidt
Alexander Laschitsch
Christian Roth
Christoph Krohmer
Helmut Häring
Detlef Birth
Original Assignee
Evonik Röhm Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Evonik Röhm Gmbh filed Critical Evonik Röhm Gmbh
Priority to EP06806924A priority Critical patent/EP1960181A1/en
Priority to US12/091,174 priority patent/US20080224339A1/en
Priority to AU2006328835A priority patent/AU2006328835A1/en
Priority to JP2008544902A priority patent/JP2009519145A/en
Priority to BRPI0619995-0A priority patent/BRPI0619995A2/en
Priority to CA002629595A priority patent/CA2629595A1/en
Publication of WO2007071467A1 publication Critical patent/WO2007071467A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
    • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
    • B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
    • B29C59/046—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts for layered or coated substantially flat surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C59/00—Surface shaping of articles, e.g. embossing; Apparatus therefor
    • B29C59/02—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing
    • B29C59/04—Surface shaping of articles, e.g. embossing; Apparatus therefor by mechanical means, e.g. pressing using rollers or endless belts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/91—Heating, e.g. for cross linking
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/911—Cooling
    • B29C48/9135—Cooling of flat articles, e.g. using specially adapted supporting means
    • B29C48/914—Cooling of flat articles, e.g. using specially adapted supporting means cooling drums
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B29K2023/0608—PE, i.e. polyethylene characterised by its density
    • B29K2023/0633—LDPE, i.e. low density polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/04—Polymers of ethylene
    • B29K2023/06—PE, i.e. polyethylene
    • B29K2023/0608—PE, i.e. polyethylene characterised by its density
    • B29K2023/065—HDPE, i.e. high density polyethylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
    • B29K2023/10—Polymers of propylene
    • B29K2023/12—PP, i.e. polypropylene
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
    • B29K2027/06—PVC, i.e. polyvinylchloride
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2033/00—Use of polymers of unsaturated acids or derivatives thereof as moulding material
    • B29K2033/04—Polymers of esters
    • B29K2033/12—Polymers of methacrylic acid esters, e.g. PMMA, i.e. polymethylmethacrylate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2067/00—Use of polyesters or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2069/00—Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2077/00—Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/25—Solid
    • B29K2105/253—Preform
    • B29K2105/256—Sheets, plates, blanks or films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
    • B29L2011/00—Optical elements, e.g. lenses, prisms

Definitions

  • the invention relates to a co-extruded plastic film with a prism structure, a process for the production of co-extruded plastic films with prism structure and their uses.
  • thermoplastics structuring of the surface is preferably achieved by the action of a stamping tool on the surface located in the corresponding temperature state.
  • a stamping tool on the surface located in the corresponding temperature state.
  • PMMA-based plastic sheet material with characteristically textured surfaces are u.a. produced by extrusion with simultaneous embossing in a three-roll calender (calender). In this case, a roller (embossing roll) is provided with the negative of the desired plate structure.
  • the goal with structured plates is to give the best possible picture of the roll structure. This goal is achieved by setting the lowest possible melt viscosity and the highest possible roller temperature. Furthermore, as practice shows, the maximum pressure in front of the narrowest point in the nip (i.e., the gap between smooth and textured roll) should be high in order to transfer as much embossing force as possible. The three conditions mentioned inevitably result in compromises in the technical implementation of the extrusion of structured sheets.
  • the roller temperature can not be increased arbitrarily, since most plastic melts stick to hot metals. From a certain roll temperature, this sticking tendency leads to separation difficulties on the embossing roll.
  • the melt viscosity of the plastic can not be chosen arbitrarily low, such as by setting high melt temperatures, otherwise the stamping force in the nip is too low.
  • Another object was to provide thin films with a textured surface.
  • the task was also to provide an economical, continuous process.
  • the object was achieved by a continuous process for the production of coextruded plastic films with a prismatic structure, characterized in that in the extrusion process, a base film having a thickness between 0.10 and 0.35 mm and a low-viscosity layer coextruded and then by means of a heatable roll calender, containing a roller with a structuring surface, the film composite is provided with a structuring.
  • a coextruded plastic film is produced by means of an extrusion line equipped with 2 extruders and a roll calender comprising a roller with a structured surface (embossing roll), a low-viscosity layer being applied to a high-viscosity base film.
  • the coextruded plastic film is then structured in the roll calender by the embossing roll.
  • embossing roll By using a high-viscosity base film, the introduction of the necessary embossing force is ensured.
  • Both base film and coextrusion layer are preferably thermoplastics.
  • Suitable thermoplastics include polyacrylates, in particular PMMA, polycarbonate, polyolefins, LDPE, HDPE, PP, polyethylene terephthalate, PVC, polystyrene, polyamide.
  • the low-viscosity coextrusion layer can advantageously consist of the same types of plastic as the base film, but it can also consist of a sufficiently compatible with this plastic. (See JE Johnson, Kunststoff Scheme K), 538-541 (1976)).
  • the melt viscosity of the coextrusion material should be that of an injection molding compound for high imaging accuracy.
  • Polycarbonate is particularly preferred since the refractive index of 1.58 is well suited for optical applications. For example, polycarbonate ensures efficient light control.
  • the coextruded layer is preferably made of a low viscosity material.
  • flow improvers may also be added to the material.
  • low molecular weight compounds are suitable, such as low molecular weight polymethylmethacrylate.
  • the MVR (melt yolumeflow rate) ratio between high-viscosity base film and low-viscosity coextrusion layer is ideally between 1:20 and 1: 8, preferably 1:10.
  • the thickness of the low-viscosity coextrusion layer depends on the function.
  • the embossing of a structure requires precisely coordinated process parameters. The possibilities of adaptation are limited: The roller temperature can not be increased arbitrarily, since most plastic melts stick to hot metals. From a certain roll temperature, this sticking tendency leads to separation difficulties on the embossing roll.
  • the melt viscosity of the plastic can not be arbitrarily low be selected, for example by setting high melt temperatures, otherwise the embossing force in the nip is too low.
  • the layer thickness of the coextrusion layer has a special influence.
  • the layer thickness should have at least a quarter of the structure height of the embossing roll.
  • release agents With an optimal adaptation of the process parameters can be dispensed with the use of release agents. Nevertheless, if the use of release agents in the coextrusion layer is required, those skilled in the art are familiar with the materials known from the prior art (HF Mark et al., Encyclopedia of Polymer Science & Engineering, Index Volume pg., 307-324, J. Wiley 1990 Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. Vol. A20, pg. 479-483, VCH 1992, R. Gaechter, H. Müller Kunststoffadditive, 3rd ed. Carl Hanser Verlag 1989).
  • the content of the release agent used with the coextrusion layer is preferably in the range from 0 to 0.34% by weight, based on the mass of coextrudate. Particular mention may be made of higher alcohols.
  • the use of a release agent in the coextrusion compound reduces the tendency of the melt to adhere to hot metal.
  • the embossing roll temperature can therefore be increased considerably in the embossing process.
  • up to 70 ° C. above the glass transition temperature Tg of the coextrusion compound may be mentioned.
  • the glass transition temperatures Tg are known or can be calculated or determined. (See Brandrup-Immergut, Polymer Handbook, Chapter V, J. Wiley, Vieweg-Esser, Kunststoff-Handbuch Vol. IX, 333-340, Carl Hanser 1975 ).
  • the process according to the invention can be carried out as follows:
  • the extrusion plant is essentially composed of a main extruder, a coextruder and a coextrusion tool.
  • the maximum width of the extruded films is determined by the coextrusion tool. In general, the extruded films are 400 to 2000 mm wide. Their thickness is also limited by the conditions of coextrusion; In general, the thickness of the base film is 0.10 to 0.35 mm, wherein the layer formed from the low-viscosity material is determined primarily by the function intended with the structuring. In general, however, their layer thickness is 0.006 to 0.075 mm.
  • the structure depth of the embossing roll is ideally between 0.025 and 0.070 mm.
  • the base molding compound brought to a suitable temperature by the main extruder and the low-viscosity molding compound brought to a suitable temperature in the coextruder are combined in the coextrusion die.
  • the coextrudate exiting the coextrusion die is passed over the roll calender, with a roll designed as an embossing roll so that its surface is the negative of the desired textured film surface. Between the pressure roller and the embossing roller is the nip. Here, the maximum pressure before the narrowest point should be high in order to transfer as much embossing force.
  • the roller calender corresponds otherwise in the prior art.
  • the extruded foils with a textured surface are transported via support rollers. Then they can be wound to the desired length and / or cut. The profile then represents an exact image of the embossing roll surface.
  • the MVR ratio of the base film to the coextruded layer is between 1:20 and 1: 8, preferably 1:10.
  • the coextruded layer may have a thickness of at least half the structural height. Contrary to DE 4407468, the thickness of the coextruded layer can be greater than the structure depth of the embossing roll.
  • One field of application for the films produced according to the invention are optical materials. Since a high-quality material is required for optical applications, this process is preferably carried out in a clean room. For the particularly interesting application as a film for the display backlighting is working in the clean room class 100, since the dust load of the ambient air would lead to unacceptable contamination of the film.
  • polycarbonate having an MVR of 6 is coextruded with a low viscosity polycarbonate having an MVR of 66.
  • the base film has a width of 1800 mm and a thickness of 150 .mu.m, the coextruded layer has a thickness of 25 .mu.m.
  • the coextrudate is passed through a heatable roll calender, here a three-roll calender, which has an embossing roll with prismatic structure.
  • the structure depth of the embossing roller is 50 ⁇ m.
  • the embossing roller is heated to about 200 0 C.
  • the coextruded film is passed over the embossing roller.
  • polycarbonate having an MVR of 6 is coextruded with a low viscosity polycarbonate having an MVR of 66.
  • the base film has a width of 400 mm and a thickness of 500 .mu.m, the coextruded layer has a thickness of 70 .mu.m.
  • the coextrudate is passed through a heatable roll calender, here a three-roll calender, which has an embossing roll with prismatic structure.
  • the structure depth of the embossing roller is 50 ⁇ m.
  • the embossing roll is set to approx. Heated to 200 ° C.
  • the coextruded film is passed over the embossing roller.
  • polycarbonate having an MVR of 3 is coextruded with a low viscosity polycarbonate having an MVR of 60.
  • the base film has a width of 400 mm and a thickness of 500 .mu.m, the coextruded layer has a thickness of 70 .mu.m.
  • the coextrudate is passed over a heatable three-roll calender having an embossing roller with a prismatic structure. The structure depth of the embossing roller is 50 ⁇ m.
  • the embossing roller is heated to about 200 0 C. At a speed of 2 m / min, the coextruded film is passed over the embossing roller.
  • polymethyl methacrylate having an MVR of 1.2 is coextruded with a low viscosity polymethyl methacrylate having an MVR of 12.
  • the base film has a width of 400 mm and a thickness of 800m, the coextruded layer has a thickness of 25 ⁇ m.
  • the coextrudate is over heatable three-roll calender led, which has an embossing roller with prismatic structure.
  • the structure depth of the embossing roller is 100 ⁇ m.
  • the embossing roller is heated to about 180 0 C. At a speed of 2 m / min, the coextruded film is passed over the embossing roller.

Abstract

The invention relates to co-extruded films of a prismatic structure, a method for producing co-extruded films of a prismatic structure and applications.

Description

Prismenfilme für optische Anwendungen Prism films for optical applications
Die Erfindung betrifft eine coextrudierte Kunststofffolie mit Prismenstruktur, ein Verfahren zur Herstellung von coextrudierten Kunststofffolien mit Prismenstruktur und deren Verwendungen.The invention relates to a co-extruded plastic film with a prism structure, a process for the production of co-extruded plastic films with prism structure and their uses.
Unter verschiedenen Gesichtspunkten hat die Technik Verfahren zur Strukturierung von Kunststoff-Oberflächen entwickelt, soweit sich der Kunststoff dafür eignet. Beispielsweise bei Thermoplasten wird eine Strukturierung der Oberfläche vorzugsweise durch Einwirkung eines Prägewerkzeugs auf die im entsprechenden Temperaturzustand befindliche Oberfläche erreicht. (Becker- Braun, Kunststoff-Handbuch, Bd. 1, 543 - 544, Hanser-Verlag 1990; K. Stockhert, Veredeln von Kunststoffoberflächen, Hanser 1975). Im Handel befindet sich u.a. Kunststoff-Tafelmaterial auf PMMA-Basis mit charakteristisch strukturierten Oberflächen. Diese werden u.a. durch Extrusion bei gleichzeitiger Prägung in einem Drei-Walzen-Glättwerk (Kalander) hergestellt. Dabei ist eine Walze (Prägewalze) mit dem Negativ der gewünschten Plattenstruktur versehen. Das Ziel ist bei strukturierten Platten eine möglichst gute Abbildung der Walzenstruktur. Man erreicht dieses Ziel durch Einstellen einer möglichst niedrigen Schmelzeviskosität und einer möglichst hohen Walzentemperatur. Desweiteren sollte - wie die Praxis zeigt - das Druckmaximum vor der engsten Stelle im Walzenspalt (d.h. dem Spalt zwischen glatter und strukturierter Walze) hoch sein, um möglichst viel Prägekraft übertragen zu können. Aus den drei genannten Bedingungen ergeben sich unabwendbar Kompromisse bei der technischen Durchführung der Extrusion strukturierter Tafeln.From various points of view, the technology has developed methods for structuring plastic surfaces, as far as the plastic is suitable. For example, in thermoplastics structuring of the surface is preferably achieved by the action of a stamping tool on the surface located in the corresponding temperature state. (Becker-Braun, Kunststoff-Handbuch, Vol. 1, 543-544, Hanser-Verlag 1990, K. Stockhert, Refining of Plastic Surfaces, Hanser 1975). In the trade u.a. PMMA-based plastic sheet material with characteristically textured surfaces. These are u.a. produced by extrusion with simultaneous embossing in a three-roll calender (calender). In this case, a roller (embossing roll) is provided with the negative of the desired plate structure. The goal with structured plates is to give the best possible picture of the roll structure. This goal is achieved by setting the lowest possible melt viscosity and the highest possible roller temperature. Furthermore, as practice shows, the maximum pressure in front of the narrowest point in the nip (i.e., the gap between smooth and textured roll) should be high in order to transfer as much embossing force as possible. The three conditions mentioned inevitably result in compromises in the technical implementation of the extrusion of structured sheets.
Die Herstellung von Kunststoffplatten mit strukturierten Oberflächen nach dem Verfahren des Standes der Technik stößt insbesondere da an ihre Grenzen, wo besonders hohe Anforderungen hinsichtlich Feinheit und Genauigkeit der Struktur gestellt werden.The production of plastic plates with textured surfaces according to the method of the prior art encounters in particular because to its limits, where particularly high demands are made in terms of fineness and accuracy of the structure.
Die Möglichkeit der Anpassung der geschilderten Randbedingungen sind limitiert: Die Walzentemperatur kann nicht beliebig erhöht werden, da die meisten Kunststoffschmelzen an heißen Metallen kleben. Diese Klebetendenz führt ab einer gewissen Walzentemperatur zu Ablöseschwierigkeiten an der Prägewalze. Die Schmelzeviskosität des Kunststoffs kann nicht beliebig niedrig gewählt werden, etwa durch Einstellung hoher Schmelzetemperaturen, da sonst die Prägekraft im Walzenspalt zu gering wird.The possibility of adapting the described boundary conditions are limited: The roller temperature can not be increased arbitrarily, since most plastic melts stick to hot metals. From a certain roll temperature, this sticking tendency leads to separation difficulties on the embossing roll. The melt viscosity of the plastic can not be chosen arbitrarily low, such as by setting high melt temperatures, otherwise the stamping force in the nip is too low.
Die Abbildegenauigkeit von Platten, die nach diesem Verfahren und mit diesen Einschränkungen produziert werden, ist für gewisse Anwendungen nicht gut genug, d.h. feine Strukturen werden nicht richtig ausgeformt oder verrunden. Es bestand daher die Aufgabe, ein Verfahren zur Herstellung von strukturierten Oberflächen zur Verfügung zu stellen, das den genannten Anforderungen, wie hohe Abbildegenauigkeit der Prägewalze bei sehr feiner Struktur der Oberfläche, genügt.The imaging accuracy of plates produced by this method and with these limitations is not good enough for certain applications, i. fine structures are not properly formed or rounded. It is an object of the present invention to provide a process for the production of structured surfaces which satisfies the stated requirements, such as high imaging accuracy of the embossing roll with a very fine structure of the surface.
Ein weiteres Problem ist die Herstellung dünner Folien mit strukturierten Oberflächen. In der DE 4407468 werden Plattendicken auf 0,5 bis 25 mm limitiert. Die Dicke der aufgebrachten niedrigviskoseren Schicht wird auf 0,2 bis 5 mm limitiert. Damit ergeben sich massive Tafeln mit Dicken von 0,7 bis 30 mm. Eine Übertragung der Technik zur Herstellung von Platten auf dünne Folien ist kaum möglich.Another problem is the production of thin films with structured surfaces. In DE 4407468 panel thicknesses are limited to 0.5 to 25 mm. The thickness of the applied lower viscosity layer is limited to 0.2 to 5 mm. This results in massive panels with thicknesses of 0.7 to 30 mm. A transfer of the technology for the production of plates on thin films is hardly possible.
Eine weitere Aufgabe bestand in der Bereitstellung dünner Folien mit einer strukturierten Oberfläche.Another object was to provide thin films with a textured surface.
In der US 5175030 wird ein Verfahren zur Herstellung von Folien mit Prismenstruktur beschrieben. Es wird in einem aufwändigen diskontinuierlichen Verfahren ein Harz auf eine fertige Folie gebracht, mit einem Master geprägt und der Verbund mit UV-Strahlung ausgehärtet. Anschließend wird der Master vom mikrostrukturierten Film getrennt. Neben den hohen Herstellkosten, auch bedingt durch die diskontinuierliche Produktion, ist ein weiterer Nachteil die eingeschränkte Foliengröße. Die maximale Mastergröße beträgt ca. 1200 x 1200 mm.In US 5175030 a process for the production of films with prismatic structure is described. It gets in an elaborate discontinuous Procedure a resin placed on a finished film, embossed with a master and cured the composite with UV radiation. Then the master is separated from the microstructured film. In addition to the high production costs, also due to the discontinuous production, another disadvantage is the limited film size. The maximum master size is approx. 1200 x 1200 mm.
Aufgabe war es zudem, ein wirtschaftliches, kontinuierliches Verfahren zur Verfügung zu stellen.The task was also to provide an economical, continuous process.
Die Aufgabe wurde gelöst durch ein kontinuierliches Verfahren zur Herstellung von coextrudierten Kunststofffolien mit Prismenstruktur, dadurch gekennzeichnet, dass im Extrusionsverfahren eine Basisfolie mit einer Dicke zwischen 0,10 und 0,35 mm und eine niedrigviskose Schicht coextrudiert und anschließend mittels eines beheizbaren Walzen-Glättwerkes, enthaltend eine Walze mit strukturgebender Oberfläche, der Folienverbund mit einer Strukturierung versehen wird.The object was achieved by a continuous process for the production of coextruded plastic films with a prismatic structure, characterized in that in the extrusion process, a base film having a thickness between 0.10 and 0.35 mm and a low-viscosity layer coextruded and then by means of a heatable roll calender, containing a roller with a structuring surface, the film composite is provided with a structuring.
Mittels einer mit 2 Extrudern und einem Walzen-Glättwerk, enthaltend eine Walze mit strukturierter Oberfläche (Prägewalze) ausgestatteten Extrusionsanlage wird eine coextrudierte Kunststofffolie hergestellt, wobei auf eine hochviskose Basisfolie eine niedrigviskose Schicht aufgebracht wird. Die coextrudierte Kunststofffolie wird anschließend im Walzen-Glättwerk durch die Prägewalze strukturiert. Durch die Verwendung einer hochviskosen Basisfolie wird die Einbringung der nötigen Prägekraft gewährleistet. Sowohl Basisfolie als auch Coextrusionsschicht sind vorzugsweise thermoplastische Kunststoffe. Als thermoplastische Kunststoffe kommen Polyacrylate, insbesondere PMMA, Polycarbonat, Polyolefine, LDPE, HDPE, PP, Polyethylenterephtalat, PVC, Polystyrol, Polyamid infrage. Die niedrigviskose Coextrusionsschicht kann vorteilhaft aus denselben Kunststofftypen bestehen, wie die Basisfolie, sie kann aber auch aus einem mit diesem hinreichend kompatiblen Kunststoff bestehen. (Vgl. J.E. Johnson, Kunststoffberater K), 538-541 (1976)). Als Regel kann gelten, daß die Schmelzviskosität des Coextrusionsmaterials der einer Spritzgußmasse für hohe Abbildegenauigkeit entsprechen soll. Besonders bevorzugt wird Polycarbonat verwendet, da der Brechungsindex von 1 ,58 für optische Anwendungen gut geeignet ist. Beispielsweise wird mit Polycarbonat eine effiziente Lichtlenkung gewährleistet.A coextruded plastic film is produced by means of an extrusion line equipped with 2 extruders and a roll calender comprising a roller with a structured surface (embossing roll), a low-viscosity layer being applied to a high-viscosity base film. The coextruded plastic film is then structured in the roll calender by the embossing roll. By using a high-viscosity base film, the introduction of the necessary embossing force is ensured. Both base film and coextrusion layer are preferably thermoplastics. Suitable thermoplastics include polyacrylates, in particular PMMA, polycarbonate, polyolefins, LDPE, HDPE, PP, polyethylene terephthalate, PVC, polystyrene, polyamide. The low-viscosity coextrusion layer can advantageously consist of the same types of plastic as the base film, but it can also consist of a sufficiently compatible with this plastic. (See JE Johnson, Kunststoffberater K), 538-541 (1976)). As a rule, the melt viscosity of the coextrusion material should be that of an injection molding compound for high imaging accuracy. Polycarbonate is particularly preferred since the refractive index of 1.58 is well suited for optical applications. For example, polycarbonate ensures efficient light control.
Die coextrudierte Schicht besteht vorzugsweise aus einem niedrigviskosen Material. Zusätzlich können dem Material auch Fließverbesserer zugegeben werden. Als Fließverbesserer sind niedermolekulare Verbindungen geeignet, wie beispielsweise niedermolekulares Polymethylmethacrylat.The coextruded layer is preferably made of a low viscosity material. In addition, flow improvers may also be added to the material. As flow improvers, low molecular weight compounds are suitable, such as low molecular weight polymethylmethacrylate.
Das MVR (melt yolumeflow rate) Verhältnis zwischen hochviskoser Basisfolie und niedrigviskoser Coextrusionsschicht liegt idealerweise zwischen 1 :20 und 1 :8, bevorzugt bei 1 :10.The MVR (melt yolumeflow rate) ratio between high-viscosity base film and low-viscosity coextrusion layer is ideally between 1:20 and 1: 8, preferably 1:10.
Die Dicke der niedrigviskosen Coextrusionsschicht ist von der Funktion abhängig. Die Prägung einer Struktur erfordert genau abgestimmte Verfahrensparameter. Die Möglichkeiten der Anpassung sind limitiert: Die Walzentemperatur kann nicht beliebig erhöht werden, da die meisten Kunststoffschmelzen an heißen Metallen kleben. Diese Klebetendenz führt ab einer gewissen Walzentemperatur zu Ablöseschwierigkeiten an der Prägewalze. Die Schmelzeviskosität des Kunststoffs kann nicht beliebig niedrig gewählt werden, etwa durch Einstellung hoher Schmelzetemperaturen, da sonst die Prägekraft im Walzenspalt zu gering wird.The thickness of the low-viscosity coextrusion layer depends on the function. The embossing of a structure requires precisely coordinated process parameters. The possibilities of adaptation are limited: The roller temperature can not be increased arbitrarily, since most plastic melts stick to hot metals. From a certain roll temperature, this sticking tendency leads to separation difficulties on the embossing roll. The melt viscosity of the plastic can not be arbitrarily low be selected, for example by setting high melt temperatures, otherwise the embossing force in the nip is too low.
Bei einer höherviskos eingestellten Coextrusionsschicht reichen die Andruckkräfte der Walzenpaare nicht aus, um eine akzeptable Prägung zu erreichen.With a coextrusion layer set to a higher viscosity, the pressure forces of the roller pairs are not sufficient to achieve an acceptable embossing.
Einen besonderen Einfluß hat daher die Schichtdicke der Coextrusionsschicht. Für eine gute Abbildung der Struktur sollte die Schichtdicke mindestens ein Viertel der Strukturhöhe der Prägewalze aufweisen.Therefore, the layer thickness of the coextrusion layer has a special influence. For a good image of the structure, the layer thickness should have at least a quarter of the structure height of the embossing roll.
Überraschend wurde gefunden, dass die Aufbringung einer sehr dicken Coextrusionsschicht aus niedrigviskosem Kunststoff zur Ausprägung einer gleichmäßigen Prismenstruktur führt, auch wenn man entgegen der Angabe in der DE4407468 mit der niedrigviskosen Coextrusionsschicht die maximale Tiefe der Struktur der der Prägewalze überschreitet.Surprisingly, it has been found that the application of a very thick coextrusion layer of low-viscosity plastic leads to the formation of a uniform prism structure, even if, contrary to what is stated in DE4407468 with the low-viscosity coextrusion layer, the maximum depth of the structure of the embossing roll is exceeded.
Bei einer optimalen Anpassung der Verfahrensparameter kann auf den Einsatz von Trennmitteln verzichtet werden. Sollte trotzdem der Einsatz von Trennmitteln in der Coextrusionsschicht erforderlich sein, stehen dem Fachmann die aus dem Stand der Technik bekannten Materialien zur Verfügung (H. F. Mark et al. Encyclopedia of Polymer Science & Engineering, Index Volume pg. 307 - 324, J. Wiley 1990; Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. Vol. A20, pg. 479 - 483, VCH 1992; R. Gaechter, H. Müller Kunststoffadditive, 3. Aufl. Carl Hanser Verlag 1989).With an optimal adaptation of the process parameters can be dispensed with the use of release agents. Nevertheless, if the use of release agents in the coextrusion layer is required, those skilled in the art are familiar with the materials known from the prior art (HF Mark et al., Encyclopedia of Polymer Science & Engineering, Index Volume pg., 307-324, J. Wiley 1990 Ullmann's Encyclopedia of Industrial Chemistry, 5th Ed. Vol. A20, pg. 479-483, VCH 1992, R. Gaechter, H. Müller Kunststoffadditive, 3rd ed. Carl Hanser Verlag 1989).
Vorzugsweise liegt der Gehalt der mit der Coextrusionsschicht eingesetzten Trennmittel im Bereich 0 bis 0,34 Gew.-% bezogen auf die Masse an Coextrudat. Genannt seien insbesondere höhere Alkohole. Durch die Verwendung eines Trennmittels in der Coextrusionsmasse sinkt die Klebeneigung der Schmelze an heißem Metall. Die Prägewalzentemperatur kann daher bei dem Prägeverfahren erheblich erhöht werden. Als Anhalt seien bis zu 70 0C über der Glastemperatur Tg der Coextrusionsmasse genannt. (Die Glastemperaturen Tg sind bekannt bzw. können rechnerisch ermittelt oder bestimmt werden. (Vgl. Brandrup-Immergut, Polymer Handbook, Chapter V, J. Wiley, Vieweg-Esser, Kunststoff-Handbuch Bd. IX, 333 - 340, Carl Hanser 1975).The content of the release agent used with the coextrusion layer is preferably in the range from 0 to 0.34% by weight, based on the mass of coextrudate. Particular mention may be made of higher alcohols. The use of a release agent in the coextrusion compound reduces the tendency of the melt to adhere to hot metal. The embossing roll temperature can therefore be increased considerably in the embossing process. As a basis, up to 70 ° C. above the glass transition temperature Tg of the coextrusion compound may be mentioned. (The glass transition temperatures Tg are known or can be calculated or determined. (See Brandrup-Immergut, Polymer Handbook, Chapter V, J. Wiley, Vieweg-Esser, Kunststoff-Handbuch Vol. IX, 333-340, Carl Hanser 1975 ).
Das erfindungsgemäße Verfahren kann wie folgt durchgeführt werden: Die Extrusionsanlage ist im wesentlichen aufgebaut aus einem Hauptextruder, einem Coextruder und einem Werkzeug zur Coextrusion.The process according to the invention can be carried out as follows: The extrusion plant is essentially composed of a main extruder, a coextruder and a coextrusion tool.
Die maximale Breite der extrudierten Folien wird durch das Coextrusions- Werkzeug bestimmt. Im allgemeinen sind die extrudierten Folien 400 bis 2000 mm breit. Ihre Dicke wird ebenfalls durch die Bedingungen der Coextrusion limitiert; im allgemeinen liegt die Dicke der Basisfolie bei 0,10 bis 0,35 mm, wobei die aus dem niedrigviskosen Material gebildete Schicht in erster Linie durch die mit der Strukturierung intendierte Funktion bestimmt wird. Im allgemeinen liegt deren Schichtdicke jedoch bei 0,006 bis 0,075 mm. Die Strukturtiefe der Prägewalze liegt idealerweise zwischen 0,025 und 0,070 mm.The maximum width of the extruded films is determined by the coextrusion tool. In general, the extruded films are 400 to 2000 mm wide. Their thickness is also limited by the conditions of coextrusion; In general, the thickness of the base film is 0.10 to 0.35 mm, wherein the layer formed from the low-viscosity material is determined primarily by the function intended with the structuring. In general, however, their layer thickness is 0.006 to 0.075 mm. The structure depth of the embossing roll is ideally between 0.025 and 0.070 mm.
Die durch den Hauptextruder auf geeignete Temperatur gebrachte Basisformmasse und die im Coextruder auf geeignete Temperatur gebrachte niedrigviskose Formmasse werden im Coextrusionswerkzeug zusammengeführt. Dabei ergeben sich für die Basisformmasse als Anhaltspunkt etwa die folgenden Düsentemperaturen: Basisform masse VerarbeitungstemperaturThe base molding compound brought to a suitable temperature by the main extruder and the low-viscosity molding compound brought to a suitable temperature in the coextruder are combined in the coextrusion die. The following are the approximate nozzle temperatures for the basic molding material as a guide: Basic shape mass processing temperature
(0C)( 0 C)
Polymethylmethacrylat 230 - 290Polymethyl methacrylate 230-290
Polystyrol 190 - 230Polystyrene 190 - 230
Polycarbonat 250 - 300Polycarbonate 250 - 300
Das aus dem Coextrusionswerkzeug austretende Coextrudat wird über das Walzen-Glättwerk geleitet, wobei eine Walze als Prägewalze derart ausgelegt ist, daß ihre Oberfläche das Negativ der gewünschten strukturierten Folienoberfläche darstellt. Zwischen der Andruckwalze und der Prägewalze befindet sich der Walzenspalt. Hier soll das Druckmaximum vor der engsten Stelle hoch sein, um möglichst viel Prägekraft übertragen zu können. Das Walzen-Glättwerk entspricht im übrigen dem Stand der Technik. Die extrudierten Folien mit strukturierter Oberfläche werden über Stützrollen transportiert. Anschließend können sie auf die gewünschte Länge gewickelt und/oder geschnitten werden. Das Profil stellt dann ein exaktes Abbild der Prägewalzenoberfläche dar.The coextrudate exiting the coextrusion die is passed over the roll calender, with a roll designed as an embossing roll so that its surface is the negative of the desired textured film surface. Between the pressure roller and the embossing roller is the nip. Here, the maximum pressure before the narrowest point should be high in order to transfer as much embossing force. The roller calender corresponds otherwise in the prior art. The extruded foils with a textured surface are transported via support rollers. Then they can be wound to the desired length and / or cut. The profile then represents an exact image of the embossing roll surface.
Es wurde gefunden, daß erstmalig beliebig lange coextrudierte Kunststofffolien mit Prismenstruktur zur Verfügung gestellt werden können, deren Basisfolie eine Dicke zwischen 0,10 und 0,35 mm aufweist.It has been found that, for the first time, it is possible to provide coextruded plastic films with a prism structure of arbitrary length, the base film of which has a thickness of between 0.10 and 0.35 mm.
Bei den coextrudierten Kunststofffolien mit Prismenstruktur liegt das MVR- Verhältnis von Basisfolie zur coextrudierten Schicht zwischen 1 :20 und 1 :8, bevorzugt bei 1 :10.In the coextruded plastic films with a prism structure, the MVR ratio of the base film to the coextruded layer is between 1:20 and 1: 8, preferably 1:10.
Die coextrudierte Schicht kann eine Dicke von mindestens der Hälfte der Strukturhöhe aufweisen. Entgegen der DE 4407468 kann die Dicke der coextrudierten Schicht größer als die Strukturtiefe der Prägewalze sein. Ein Anwendungsgebiet für die erfindungsgemäß hergestellten Folien sind optische Materialien. Da für optische Anwendungen ein qualitativ hochwertiges Material erforderlich ist, wird dieses Verfahren bevorzugt im Reinraum durchgeführt. Für die besonders interessante Anwendung als Folie für die Displayhinterleuchtung wird im Reinraum der Klasse 100 gearbeitet, da die Staubbelastung der Umgebungsluft zur nicht akzeptablen Verschmutzung der Folie führen würde.The coextruded layer may have a thickness of at least half the structural height. Contrary to DE 4407468, the thickness of the coextruded layer can be greater than the structure depth of the embossing roll. One field of application for the films produced according to the invention are optical materials. Since a high-quality material is required for optical applications, this process is preferably carried out in a clean room. For the particularly interesting application as a film for the display backlighting is working in the clean room class 100, since the dust load of the ambient air would lead to unacceptable contamination of the film.
Die im Folgenden gegebenen Beispiele werden zur besseren Veranschaulichung der vorliegenden Erfindung gegeben, sind jedoch nicht dazu geeignet, die Erfindung auf die hierin offenbarten Merkmale zu beschränken. The examples given below are given for a better illustration of the present invention, but are not intended to limit the invention to the features disclosed herein.
BEISPIELEEXAMPLES
Beispiel 1 :Example 1 :
In einer Coextrusionsanlage wird Polycarbonat mit einem MVR-Wert von 6 mit einem niedrigviskosen Polycarbonat mit einem MVR-Wert von 66 coextrudiert.In a coextrusion line, polycarbonate having an MVR of 6 is coextruded with a low viscosity polycarbonate having an MVR of 66.
Die Basisfolie hat eine Breite von 1800 mm und eine Dicke von 150μm, die coextrudierte Schicht eine Dicke von 25μm.The base film has a width of 1800 mm and a thickness of 150 .mu.m, the coextruded layer has a thickness of 25 .mu.m.
Das Coextrudat wird über ein beheizbares Walzen-Glättwerk, hier ein Dreiwalzen-Glättwerk, geführt, das eine Prägewalze mit Prismenstruktur besitzt. Die Strukturtiefe der Prägewalze beträgt 50μm. Die Prägewalze wird auf ca. 2000C erwärmt. Mit einer Geschwindigkeit von 20 m/min wird die coextrudierte Folie über die Prägewalze geführt.The coextrudate is passed through a heatable roll calender, here a three-roll calender, which has an embossing roll with prismatic structure. The structure depth of the embossing roller is 50μm. The embossing roller is heated to about 200 0 C. At a speed of 20 m / min, the coextruded film is passed over the embossing roller.
Es wird eine coextrudierte Kunststofffolie aus Polycarbonat mit einer sehr guten Abformung der Prismenstruktur erhalten, die für optische Anwendungen, beispielsweise für Displayhinterleuchtungen geeignet sind.It is obtained a coextruded plastic film made of polycarbonate with a very good impression of the prismatic structure, which are suitable for optical applications, for example, display backlights.
Beispiel 2:Example 2:
In einer Coextrusionsanlage wird Polycarbonat mit einem MVR-Wert von 6 mit einem niedrigviskosen Polycarbonat mit einem MVR-Wert von 66 coextrudiert.In a coextrusion line, polycarbonate having an MVR of 6 is coextruded with a low viscosity polycarbonate having an MVR of 66.
Die Basisfolie hat eine Breite von 400 mm und eine Dicke von 500μm, die coextrudierte Schicht eine Dicke von 70μm.The base film has a width of 400 mm and a thickness of 500 .mu.m, the coextruded layer has a thickness of 70 .mu.m.
Das Coextrudat wird über ein beheizbares Walzen-Glättwerk, hier ein Dreiwalzen-Glättwerk, geführt, das eine Prägewalze mit Prismenstruktur besitzt. Die Strukturtiefe der Prägewalze beträgt 50μm. Die Prägewalze wird auf ca. 200°C erwärmt. Mit einer Geschwindigkeit von 2 m/min wird die coextrudierte Folie über die Prägewalze geführt.The coextrudate is passed through a heatable roll calender, here a three-roll calender, which has an embossing roll with prismatic structure. The structure depth of the embossing roller is 50μm. The embossing roll is set to approx. Heated to 200 ° C. At a speed of 2 m / min, the coextruded film is passed over the embossing roller.
Es wird eine coextrudierte Kunststofffolie aus Polycarbonat mit einer sehr guten Abformung der Prismenstruktur erhalten, die für optische Anwendungen, beispielsweise für Displayhinterleuchtungen geeignet sind.It is obtained a coextruded plastic film made of polycarbonate with a very good impression of the prismatic structure, which are suitable for optical applications, for example, display backlights.
Beispiel 3:Example 3:
In einer Coextrusionsanlage wird Polycarbonat mit einem MVR-Wert von 3 mit einem niedrigviskosen Polycarbonat mit einem MVR-Wert von 60 coextrudiert.In a coextrusion line, polycarbonate having an MVR of 3 is coextruded with a low viscosity polycarbonate having an MVR of 60.
Die Basisfolie hat eine Breite von 400 mm und eine Dicke von 500μm, die coextrudierte Schicht eine Dicke von 70μm. Das Coextrudat wird über ein beheizbares Dreiwalzen-Glättwerk geführt, das eine Prägewalze mit Prismenstruktur besitzt. Die Strukturtiefe der Prägewalze beträgt 50μm.The base film has a width of 400 mm and a thickness of 500 .mu.m, the coextruded layer has a thickness of 70 .mu.m. The coextrudate is passed over a heatable three-roll calender having an embossing roller with a prismatic structure. The structure depth of the embossing roller is 50μm.
Die Prägewalze wird auf ca. 2000C erwärmt. Mit einer Geschwindigkeit von 2 m/min wird die coextrudierte Folie über die Prägewalze geführt.The embossing roller is heated to about 200 0 C. At a speed of 2 m / min, the coextruded film is passed over the embossing roller.
Es wird eine coextrudierte Kunststofffolie aus Polycarbonat mit einer sehr guten Abformung der Prismenstruktur erhalten, die für optische Anwendungen, beispielsweise für Displayhinterleuchtungen geeignet sindIt is obtained a coextruded plastic film made of polycarbonate with a very good impression of the prismatic structure, which are suitable for optical applications, for example, display backlights
Beispiel 4:Example 4:
In einer Coextrusionsanlage wird Polymethylmetacrylat mit einem MVR-Wert von 1 ,2 mit einem niedrigviskosen Polymethylmetacrylat mit einem MVR-Wert von 12 coextrudiert.In a coextrusion plant, polymethyl methacrylate having an MVR of 1.2 is coextruded with a low viscosity polymethyl methacrylate having an MVR of 12.
Die Basisfolie hat eine Breite von 400 mm und eine Dicke von 800m, die coextrudierte Schicht eine Dicke von 25μm. Das Coextrudat wird über ein beheizbares Dreiwalzen-Glättwerk geführt, das eine Prägewalze mit Prismenstruktur besitzt. Die Strukturtiefe der Prägewalze beträgt 100μm.The base film has a width of 400 mm and a thickness of 800m, the coextruded layer has a thickness of 25μm. The coextrudate is over heatable three-roll calender led, which has an embossing roller with prismatic structure. The structure depth of the embossing roller is 100μm.
Die Prägewalze wird auf ca. 1800C erwärmt. Mit einer Geschwindigkeit von 2 m/min wird die coextrudierte Folie über die Prägewalze geführt.The embossing roller is heated to about 180 0 C. At a speed of 2 m / min, the coextruded film is passed over the embossing roller.
Es wird eine coextrudierte Kunststofffolie aus Polymethylmetacrylat mit einer sehr guten Abformung der Prismenstruktur erhalten. It is obtained a coextruded plastic film of polymethylmethacrylate with a very good impression of the prismatic structure.

Claims

PATENTANSPRÜCHE
1. Kontinuierliches Verfahren zur Herstellung von coextrudierten1. Continuous process for the preparation of coextruded
Kunststofffolien mit Prismenstruktur, dadurch gekennzeichnet, dass im Extrusionsverfahren eine Basisfolie mit einer Dicke zwischen 0,10 und 0,35 mm und eine niedrigviskose Schicht coextrudiert und anschließend mittels eines beheizbaren Walzen-Glättwerkes, enthaltend eine Walze mit strukturgebender Oberfläche, der Folienverbund mit einer Strukturierung versehen wird.Plastic films with prismatic structure, characterized in that extruded in the extrusion process, a base film having a thickness between 0.10 and 0.35 mm and a low-viscosity layer and then by means of a heatable roll calender, comprising a roller with a structuring surface, the film composite with a structuring is provided.
2. Kontinuierliches Verfahren zur Herstellung von coextrudierten Kunststofffolien gemäß Anspruch 1 , dadurch gekennzeichnet, dass im Extrusionsverfahren eine Basisfolie mit einer Dicke zwischen 0,10 und 0,35 mm und eine niedrigviskose Schicht mit einer Dicke, die mindestens ein Viertel der Strukturhöhe aufweist coextrudiert werden.2. A continuous process for the production of coextruded plastic films according to claim 1, characterized in that in the extrusion process, a base film having a thickness between 0.10 and 0.35 mm and a low-viscosity layer having a thickness which has at least a quarter of the structural height are coextruded ,
3. Kontinuierliches Verfahren zur Herstellung von coextrudierten Kunststofffolien gemäß Anspruch 2, dadurch gekennzeichnet, dass im Extrusionsverfahren eine Basisfolie und eine niedrigviskose Schicht mit einer Dicke, die stärker als die Strukturhöhe ist, coextrudiert wird.3. A continuous process for the production of co-extruded plastic films according to claim 2, characterized in that in the extrusion process, a base film and a low-viscosity layer having a thickness which is greater than the structural height, is coextruded.
4. Kontinuierliches Verfahren zur Herstellung von coextrudierten Kunststofffolien gemäß Anspruch 1 , dadurch gekennzeichnet, dass das MVR-Verhältnis von Basisfolie und niedrigviskoser Schicht zwischen 1 :8 und 1 :20 liegt.4. A continuous process for the production of coextruded plastic films according to claim 1, characterized in that the MVR ratio of the base film and the low-viscosity layer is between 1: 8 and 1:20.
5. Kontinuierliches Verfahren zur Herstellung von coextrudierten Kunststofffolien gemäß Anspruch 1 , dadurch gekennzeichnet, dass die Temperatur der Prägewalze bis zu 70 °C über der Glastemperatur der Coextrusionsmasse liegt.5. A continuous process for the production of coextruded plastic films according to claim 1, characterized in that the Temperature of the embossing roll is up to 70 ° C above the glass transition temperature of the coextrusion.
6. Kontinuierliches Verfahren zur Herstellung von coextrudierten Kunststofffolien gemäß Anspruch 1 , dadurch gekennzeichnet, dass die Coextrusionsmasse noch Trennmittel enthält.6. Continuous process for the preparation of coextruded plastic films according to claim 1, characterized in that the coextrusion compound still contains release agent.
7. Coextrudierte Kunststofffolie mit Prismenstruktur, dadurch gekennzeichnet, dass die Basisfolie eine Dicke zwischen 0,10 und 0,35 mm aufweist.7. coextruded plastic film with prismatic structure, characterized in that the base film has a thickness between 0.10 and 0.35 mm.
8. Coextrudierte Kunststofffolie mit Prismenstruktur, dadurch gekennzeichnet, dass das MVR-Verhältnis von Basisfolie zu einer coextrudierten Schicht zwischen 1 :20 und 1 :8 liegt.8. Coextruded plastic film with prism structure, characterized in that the MVR ratio of base film to a coextruded layer is between 1:20 and 1: 8.
9. Coextrudierte Kunststofffolie gemäß Anspruch 7, dadurch gekennzeichnet, dass das MVR-Verhältnis von Basisfolie zu coextrudierter Schicht bei 1 :10 liegt.9. Coextruded plastic film according to claim 7, characterized in that the MVR ratio of base film to coextruded layer is 1:10.
10. Coextrudierte Kunststofffolie gemäß Anspruch 7, dadurch gekennzeichnet, dass die Dicke der coextrudierten Schicht mindestens ein Viertel der Strukturhöhe aufweist.10. Coextruded plastic film according to claim 7, characterized in that the thickness of the coextruded layer has at least a quarter of the structural height.
11. Coextrudierte Kunststofffolie gemäß Anspruch 7, dadurch gekennzeichnet, dass die Dicke der coextrudierten Schicht größer als die Strukturtiefe ist.Coextruded plastic film according to claim 7, characterized in that the thickness of the coextruded layer is greater than the texture depth.
12. Verwendung der coextrudierten Kunststofffolien hergestellt nach dem Verfahren nach Anspruch 1 für optische Anwendungen.12. Use of the coextruded plastic films produced by the method according to claim 1 for optical applications.
13. Verwendung der coextrudierten Kunststofffolien hergestellt nach dem Verfahren nach Anspruch 1 für Displayhinterleuchtungen. 13. Use of the coextruded plastic films produced by the method according to claim 1 for display backlights.
PCT/EP2006/066963 2005-12-16 2006-10-02 Prismatic films for optical applications WO2007071467A1 (en)

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EP06806924A EP1960181A1 (en) 2005-12-16 2006-10-02 Prismatic films for optical applications
US12/091,174 US20080224339A1 (en) 2005-12-16 2006-10-02 Prismatic Films for Optical Applications
AU2006328835A AU2006328835A1 (en) 2005-12-16 2006-10-02 Prismatic films for optical applications
JP2008544902A JP2009519145A (en) 2005-12-16 2006-10-02 Prism film for optical applications
BRPI0619995-0A BRPI0619995A2 (en) 2005-12-16 2006-10-02 continuous process for producing prism-structure coextruded plastic sheets, prism-structure coextruded plastic sheet its use
CA002629595A CA2629595A1 (en) 2005-12-16 2006-10-02 Prism films for optical applications

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